Regarding nRF52832 timer,ppi and gpiote tasks

RE: Regarding nRF52832 timer,ppi and gpiote tasks

Prajapati — Wed, 03 Apr 2019 14:51:56 GMT

Dear David,

Thanks for your reply,

I apologize for late reply,

I have used the nrf_vt() library at that time but i am facing some problem as before. I tried it further but getting the same problem. I compile the demo code but getting the error in app_sched_execute() ->event_handler (p_event_data,event_data_size).The error is NRF_FAULT_ID_SDK_ERROR in app_error_weak.c file. I tried a lot but can't get the result. So kindly give me some suggestion on that.

I also want to know that is this example using UART frontend or not ? Can you explain me meaning of UART frontend in brief?

thanks,

Hasmukh

RE: Regarding nRF52832 timer,ppi and gpiote tasks

David Edwin — Thu, 21 Mar 2019 15:21:49 GMT

Can you look at the previous delivery to see if that will work for you. The PWM and ADC is a far simpler to way to get the software UART.
I see the case that you opened earlier. Please confirm if that will work for you.

RE: Regarding nRF52832 timer,ppi and gpiote tasks

Kenneth — Wed, 20 Mar 2019 06:06:00 GMT

Do the two UART interfaces have to work simultaneously? Or can you use the same UART and switch pins? I guess you have already considered this.

You may also consider using the nRF52840, which have 2 UART interfaces.

[quote user="Prajapati"]HITOLO then nRF52832 internally make UART TX pin high for around 6 microseconds and then make it lo for around 45 microseconds[/quote]

The pin likely fall back to the GPIO configuration when re-configuring GPIOTE, so you make sure that you set GPIO to output and right level (low or high) before you change GPIOTE configuration.

RE: Regarding nRF52832 timer,ppi and gpiote tasks

Prajapati — Wed, 20 Mar 2019 05:34:59 GMT

Thanks for your reply,

We are using nrf52832 which has one Hardware UART. This Hardware UART is already occupied for other peripheral.

And we need another UART for MAX1472 RF transmitter so we go for software UART concept. We already implemented software UART code for 19200 bd. We are using internal 16 Mhz clock frequency so bit width is around 52.08 microseconds. The bit width gets changed while capturing the frames from the receiver side. So some frames are missed by the RF receiver. Our requirement is to bring maximum accuracy in bitwidth so we have thought to go for ppi task concept.

There is another problem in changing gpiote task. if UART TX pin is already low and our next bit is 0 means UART TX pin should be low for the next 52 microseconds and we will assign gpiote task with polarity HITOLO then nRF52832 internally make UART TX pin high for around 6 microseconds and then make it lo for around 45 microseconds. So we get 6 microsecond spikes in between the frame.

So kindly give some guidance for the same.

thanks

Hasmukh

RE: Regarding nRF52832 timer,ppi and gpiote tasks

Kenneth — Tue, 19 Mar 2019 15:02:15 GMT

After thinking about it, I am not sure how well using gpiote will work, the problem is that only one gpiote task can be connected to a specific pin. So only one compare event can control a pin, and you would need to update the gpiote task (to set or clear) for each compare event.

Maybe you can use the PWM to create UART output, I can check internally if someone may have suggestions on how to do that.

Out of curiosity, why can't you use the UART peripheral here to create 19200 baud?

RE: Regarding nRF52832 timer,ppi and gpiote tasks

Prajapati — Tue, 19 Mar 2019 14:00:24 GMT

Thanks for your quick reply,

i want to ask that Is that possible to allocate a GPIOTE task (set,reset,toggle) for timer compare event 1 in timer compare event 0 ?

Can you give me any suggestion for the same?

RE: Regarding nRF52832 timer,ppi and gpiote tasks

Kenneth — Tue, 19 Mar 2019 12:11:21 GMT

Hi,

If you want PPI to control a GPIO (e.g. timer event->ppi->toggle/set/clear pin), then you need to take a look at the GPIOTE module:
http://infocenter.nordicsemi.com/topic/com.nordic.infocenter.nrf52832.ps.v1.1/gpiote.html?cp=2_1_0_20#concept_knz_kww_lr

The GPIOTE can execute the configured task on the specific GPIO by connecting a event through a PPI channel to the task. In general more information on PPI:
http://infocenter.nordicsemi.com/topic/com.nordic.infocenter.nrf52832.ps.v1.1/ppi.html?cp=2_1_0_21#concept_sxf_21l_1s

You may take a look at the \examples\peripheral\gpiote in the nRF5 SDK.

Best regards,
Kenneth